diff --git a/lib/chibi/filesystem.sld b/lib/chibi/filesystem.sld
index cee82d27..b3b28538 100644
--- a/lib/chibi/filesystem.sld
+++ b/lib/chibi/filesystem.sld
@@ -30,7 +30,7 @@
           open/read        open/write             open/read-write
           open/create      open/exclusive         open/truncate
           open/append      open/non-block
-          file-lock
+          file-lock        file-truncate
           lock/shared lock/exclusive lock/non-blocking lock/unlock
           is-a-tty?)
   (import (chibi) (chibi string))
diff --git a/lib/chibi/filesystem.stub b/lib/chibi/filesystem.stub
index 89dddbe6..b26d8138 100644
--- a/lib/chibi/filesystem.stub
+++ b/lib/chibi/filesystem.stub
@@ -188,6 +188,11 @@
 ;;> File opening modes.
 ;;/
 
+;;> Truncate the file to the given size.
+
+(define-c int (file-truncate "ftruncate")
+  (port-or-fileno off_t))
+
 ;;> Applies the specified locking operation using flock(2) to the port
 ;;> or file-descriptor.
 
diff --git a/tests/filesystem-tests.scm b/tests/filesystem-tests.scm
new file mode 100644
index 00000000..459f30cb
--- /dev/null
+++ b/tests/filesystem-tests.scm
@@ -0,0 +1,74 @@
+
+(import (chibi) (chibi io) (chibi filesystem) (chibi test) (srfi 33))
+
+(test-begin "filesystem")
+
+(define tmp-file "/tmp/chibi-fs-test-0123456789")
+(define tmp-file2 "/tmp/chibi-fs-test-0123456789-2")
+(define tmp-link "/tmp/chibi-fs-test-0123456789-link")
+(define tmp-dir "/tmp/chibi-fs-test-0123456789-dir")
+
+(call-with-output-file tmp-file
+  (lambda (out) (display "0123456789" out)))
+
+(test-assert (file-exists? tmp-file))
+(test "0123456789" (call-with-input-file tmp-file port->string))
+
+;; call-with-output-file truncates
+(call-with-output-file tmp-file
+  (lambda (out) (display "xxxxx" out)))
+(test "xxxxx" (call-with-input-file tmp-file port->string))
+
+(call-with-output-file tmp-file
+  (lambda (out) (display "0123456789" out)))
+(test "0123456789" (call-with-input-file tmp-file port->string))
+
+;; open without open/truncate writes in place
+(let* ((fd (open tmp-file open/write))
+       (out (open-output-file-descriptor fd)))
+  (display "xxxxx" out)
+  (close-output-port out))
+(test "xxxxx56789" (call-with-input-file tmp-file port->string))
+
+;; file-truncate can explicitly truncate
+(let* ((fd (open tmp-file open/write))
+       (out (open-output-file-descriptor fd)))
+  (display "01234" out)
+  (file-truncate out 7)
+  (close-output-port out))
+(test "0123456" (call-with-input-file tmp-file port->string))
+
+;; symbolic links
+(test-assert (symbolic-link-file tmp-file tmp-link))
+(test-assert (file-exists? tmp-link))
+(test-assert (file-link? tmp-link))
+(test tmp-file (read-link tmp-link))
+
+;; rename
+(test-assert (rename-file tmp-file tmp-file2))
+(test-not (file-exists? tmp-file))
+(test-not (file-exists? tmp-link))
+(test-assert (file-link? tmp-link))
+(test-assert (delete-file tmp-link))
+(test-not (file-exists? tmp-link))
+
+;; cleanup
+(test-assert (delete-file tmp-file2))
+(test-not (file-exists? tmp-file2))
+
+;; directories
+(test-assert (file-directory? "."))
+(test-assert (file-directory? ".."))
+(test-assert (file-directory? "/"))
+(test-not (file-regular? "."))
+(test-assert (create-directory tmp-dir))
+(test-assert (file-directory? tmp-dir))
+(test-not (file-regular? tmp-dir))
+(test-assert
+  (let ((files (directory-files tmp-dir)))
+    (or (equal? files '("." ".."))
+        (equal? files '(".." ".")))))
+(test-assert (delete-directory tmp-dir))
+(test-not (file-directory? tmp-dir))
+
+(test-end)